Abstract
Aiming at monitoring of lower limb movement, a MEMS integrated chip packaged in a sensing suit and a thin film pressure sensor packaged in a sensing insole are used to collect lower limb motion information. However, it was found that there was a huge error in the measurement of pressure when using the film-based pressure sensors to monitor the foot pressure in the lower limb movement. Hence, this paper describes a method for calibration of soft pressure sensors and characterizes the pressure through the proposed approach. The results show that there is a nonlinear relationship between the input (pressure) and the output (inverse value of the electrical resistance); the fitting error is about 5.5%; the hysteresis is around 4.2%;the zero drift is about 0.11%; the repeatability error is nearly 10.7% and the uncertainty of the sensor is about 14.64%. Therefore, it suggests that there often are notable repeatability errors and sensor uncertainty in the soft thin film pressure sensors, which would affect the accuracy in the monitoring of lower limb movements.
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